Research Interests

1. Physiological basis of life-history traits and trade-offs

Over 70 years ago, Fisher highlighted the importance of an understanding of physiological mechanism to life-history theory, a point subsequently repeated by many evolutionary biologists. Despite this frequent recognition the physiological basis of most, if not all, trade-offs remains unknown. The development of the field of "evolutionary physiology" and more recently "evolutionary endocrinology" has lead to significant, and very productive, integration of physiology and evolutionary biology, although much of this work has focused on performance-related traits (e.g. sprint speed, maximum sustainable metabolic rate), rather than life-history traits. Much of the work in my lab is aimed at integration of physiology with evolutionary biology to understand mechanisms underlying variation in key LH traits (egg/offspring size and number) and trade-offs between these traits, such as that between egg size and clutch size, or the "cost of reproduction": the trade-off between current reproduction and future fecundity and/or survival.

We mainly focus on avian reproduction (though not exclusively!) and specifically early stages of reproduction (e.g. egg formation and laying) since the importance of this phase of breeding has been neglected and underestimated. Our research primarily combines laboratory studies, using captive breeding zebra finches (Taeniopygia guttata), with studies of a free-living, nest-box breeding, population of European starlings (Sturnus vulgaris) which are ideal for experimental studies in the field. However, we have been involved in other projects on a wide range of species including Arctic-nesting ducks and geese, seabirds, and even blue tits. Some recent or current projects include:

Hormonally-mediated maternal effects: through correlative studies and experimental manipulations we have been investigating the role of non-androgens, especially estradiol and corticosterone, in mediating maternal effects via transfer of maternal hormones to yolk, and subsequent effects on offspring phenotype. For example, work by Love at al. (2005) has suggested that maternal stress hormones such as corticosterone provide a mechanistic link between maternal quality and sex-biased maternal investment in offspring. In relation to estradiol, the primary female reproductive hormone, we are investigating whether negative pleiotropic effects of this hormone required for egg production include anemia - which is commonly associated with reproduction - and if this provides a potential physiological mechanism for "cost of reproduction" (Williams et al. 2004).

Molecular basis of individual variation in reproduction: with the availability of the zebra finch genome http://www.ncbi.nlm.nih.gov/genome/guide/finch/ we have started to investigate individual variation in molecular and cell-level processes involved in egg production. For example, we are characterising 1) individual variation in vitellogenin receptor (VTG-R) expression in developing follicles in the ovary, in relation to different stages of follicle development and individual variation in follicle size; and 2) individual variation in yolk-targeted very low density lipoprotein (VLDLy) expression in the liver as well as developing an ELISA for apoVLDL-II to directly assay plasma VLDLy.

Costs of egg production in song sparrows: Zanette et al. (2006 Ecology) reported a strong negative correlation between clutch number and clutch size in song sparrows breeding in the Gulf Islands, BC, indicative of a cost of reproduction at the intra-specific level. In a collaborative project with Drs. Liana Zanette and Mike Clinchy (UWO) we will test the hypothesis that this trade-off is due to an accumulated physiological cost of successive bouts of egg production, associated with pleiotropic hormone effects. Specifically we will compare reproductive success (including egg and offspring quality, sex ratio, etc) and physiological traits (including anemia, oxidative stress, plasma metabolites) in control females and females experimentally forced to re-nest.

Individual variation in reproductive effort and fitness in lady beetles: We have initiated some work with lady beetles (Harmonia axyridis) to provide a system where we can still take physiological approaches but where we can also measure recruitment, lifetime reproductive success, or survival of individual females (something that is more difficult in our avian study systems). We are characterising intra- and inter-individual variability in egg and batch (clutch) size by experimentally manipulating resource level (aphid food supply), and have obtained preliminary data demonstrating a strong positive relationship between egg size and larval survival. As is the case with avian egg size advances in theory have substantially outpaced empirical data with regard to evolution of progeny size, and specifically the causes and consequences of large inter-individual variation in egg size - which affect total fecundity - remain poorly understood.

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2. Physiology of migration

Since arriving at SFU I have been involved in a range of studies of physiological mechanisms involved in long-distance migration in Arctic-nesting shorebirds, focusing on the western sandpiper (Calidris mauri). Projects have included, a) intraspecific variation in body composition and organ masses in relation to variable energy demands during migration; b) the role of fatty acid binding protein (FABP) in migration, an intracellular protein which facilitates the delivery of fuel to the mitochondria during muscle function; this has involved isolation and characterization of avian FABP; c) the functional significance and regulation of seasonal and individual variation in fatty acid and phospholipid composition in plasma, adipose and muscle tissue, and d) the functional significance, and fitness consequences, of age-specific variation in gut morphology and physiology in first-year versus adult birds. Current work is mainly aimed at using plasma metabolite profiles (triglycerides, etc) as a tool to estimate fattening rates and provide information on habitat quality and habitat use by migratory shorebirds. I am involved in many collaborative projects, with researchers from PRBO Conservation Science, USGS and US F & W, at sites along the Pacific Flyway from California to Alaska.

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3. NSERC/CWS Chair in Wildlife Ecology: Applied Physiology  CWE web site

The mandate of the NSERC/Environment Canada Chair in Wildlife Ecology (CWE) is to foster high-quality graduate level research in wildlife ecology with specializations in behavioral, population, and physiological ecology. The central concept is to provide an interface between the mission-orientated research and management policies of the Environment Canada and the more basic-science approach of the Universities. My contribution to the Chair's mandate has been based on the belief that a rigorous understanding of the mechanisms underlying intraspecific variability in physiological traits is essential in determining, and hopefully predicting, the ability of individuals, populations and species to respond to environmental change. Specifically I have an on-going interest in the effects of pesticides and other xenobiotics on avian reproduction, in collaboration with Dr. John Elliott, Environment Canada. Some recent projects have included:

Monitoring of chlorinated hydrocarbons and effects in bald eagles on the British Columbia coast. The aim of this project was to assess the impact of chlorinated hydrocarbon concentrations on nestling bald eagles from the Lower Fraser Valley and reference sites in the Georgia Basin. The objectives of the study were to: (1) to revisit eagle nests sampled in the early 1990s to assess burdens of pulp mill related contaminants (dioxins, furans), (2) to sample those same sites for “new” chemicals of concern such as polybrominated diphenyl ethers (flame retardents) and look for correlative evidence of impairment of thyroid hormone processes. Long term trend monitoring of persistent contaminants in local marine and estuarine food chains is valuable to a variety of agencies and NGOs in assessing chemical risks to ecosystems.

Impact of use of MSMA (monosodium methanearsonate) for bark beetle control on cavity-nesting birds in B.C. forests. The infestation of BC forests by bark beetles, particularly mountain pine beetle, is a serious environmental problem and one of the options for controlling MPB is the arsenic-based insecticide MSMA. Toxicity of MSMA to select mammals and aquatic species is known but there are few studies on insectivorous birds, particularly woodpeckers which are attracted to beetle outbreaks. We tackled this problem through a combination of field work on woodpeckers and chickadees in Merrit, BC, and lab studies to investigate uptake, elimination and toxicity of MSMA in adult zebra finches and sub-lethal effects during growth in nestling zebra finches.